How to Set Proxy from Active Directory

Kindly advise me how to set proxi from Active Directory. If I just use the GPO to set and enable to the proxy setting, the proxy setting are set and enable correctly, but the user can go into the settings and dis enable them, so how to set permanently.

Using AD is not the correct solution.
Adjust your DHCP to make your gateway the IP of the proxy server. Make sure your proxy server has 2 NICs. Connect one NIC to your network and the other to your router.

Using this method, no proxy settings are needed on the client machines since ALL traffic must be routed through the proxy server in order to reach the internet.